1. Field of the Invention
The present invention relates to a temperature distribution measurement apparatus that utilizes a pyroelectric type infrared sensor and its application to a human body detecting system.
2. Discussion of Related Art
In recent years, demand has developed for devices and methods to measure room temperature distribution to detect the presence of human beings and their motion in a room. Such devices and methods find use in maintaining security, controlling air conditioning and similar applications.
Several methods have been developed to measure temperature distribution in an area which utilize infrared radiation. One of the known methods uses an application of two dimensional quantum effect type solid state infrared image sensors and another an application of pyroelectric infrared sensors.
The quantum effect type sensor provides high accuracy and high resolution temperature distribution measurement but the sensor requires a cooling system which is too costly for use with home applications.
A method exists for determining the temperature distribution in an area by detecting input energy of one direction after another through a single pyroelectric sensor that performs directional scanning vertically as well as horizontally (see Japanese Laid-Open Patent Nos. 57-185695, 2-183752, 2-196932, U.S. Pat. Nos. 5,159,200, 4,791,297 and 4,907,895).
The pyroelectric sensor has the disadvantages of low resolution in space and temperature, which result from low sensitivity, high complexity of construction, and difficult signal processing.